Solid material gasification method, thin film formation process and apparatuses

ABSTRACT

Solid material gasification method comprises a solution preparation step wherein a first solid material is dissolved in a solvent to prepare a gasification solution, a solvent removal step wherein a second solid material is separated by removing the solvent used to prepare the gasification solution from that solution, and a solid sublimation step wherein the second solid material is gasified by sublimation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 10/662,474,filed Sep. 16, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid material gasification methodand apparatus as well as a thin film formation process and apparatus.The present invention can be advantageously used for CVD and other thinfilm formation processes, and is therefore useful in the production ofsemiconductor devices and so forth.

2. Description of the Related Art

One of the production steps of semiconductor devices includes a processfor forming a thin film by gasifying a solid raw material, and suchprocesses are commonly known and widely used. In addition, knownexamples of such thin film formation processes include sputtering,vacuum vapor deposition and chemical vapor deposition (CVD). In suchthin film formation processes, the following types of processes aregenerally used to gasify solid raw materials. For example, in the caseof forming a thin film of an oxide of an organometallic compound on thesurface of a substrate by CVD, after sublimating the solid raw material(powder), the generated reactive gas is introduced into a CVD device andadhered onto a treated substrate (see, Japanese Unexamined PatentPublication (Kokai) No. 5-311446). In addition, after dissolving thesolid raw material in a solvent such as tetrahydrofuran (THF), butylacetate or hexane, the resulting solution is vaporized and introducedinto a CVD device where it can also be adhered to a treated substrate(see, Japanese Unexamined Patent Publication (Kokai) Nos. 7-76778 and10-298762).

However, in these conventional thin film formation processes, severalimportant problems remain unresolved. For example, in the case ofcarrying out thin film formation using a sublimation process, as thesolid raw material must be maintained in a heated state at all times, itis difficult to avoid deterioration of the composition and properties ofthe thin film attributable to decomposition of the raw material. Inaddition, in the case of a using a solvent vaporization process, thereis the problem of the generation of residue and particles caused byseparation and vaporization of solvent. Moreover, there are also casesin which film deposition is inhibited during the early stages of thinfilm formation due to the reducing action of the solvent.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a solid materialgasification method that enables stable and simple gasification of asolid raw material.

In addition, another object of the present invention is to provide anapparatus that is useful for carrying out such a gasification method.

Moreover, another object of the present invention is to provide a thinfilm formation process that enables simple and stable film formationunaccompanied by deterioration of composition or properties during thinfilm formation or the generation of residue and particles.

Furthermore, still another object of the present invention is to providean apparatus that is useful for carrying out such a thin film formationprocess.

As a result of conducting earnest research to find a method that did notrequire the use of a sublimation process or solvent vaporization processof the prior art, in the case of preparing a reactive gas used for thinfilm formation and so forth by gasifying from a solid material, theinventors of the present invention found that sequentially carrying outthe gasification of a solid material in a stepwise manner, namely,

a step wherein a gasification solution is prepared by dissolving a solidraw material (referred to as a “first solid material” in particular inthe present specification) in a solvent,

a step wherein the gasification solution is heated to a prescribedtemperature and the solvent is removed to recover the solid material (orin other words, a step in which only the solvent is vaporized), and

a step wherein the solid material remaining following removal of solvent(referred to as a “second solid material” in particular in the presentspecification) is sublimated and gasified by heating to a prescribedtemperature,

is effective for this purpose, thereby leading to completion of thepresent invention as explained in detail below.

According to one aspect of the present invention, there is provided asolid material gasification method comprising:

a solution preparation step wherein a first solid material is dissolvedin a solvent to prepare a gasification solution,

a solvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, and

a solid sublimation step wherein the second solid material is gasifiedby sublimation.

In addition, in another aspect of the present invention, there isprovided an apparatus for gasifying a solid material comprising:

a solvent removal chamber provided with an inlet port for a gasificationsolvent containing a first solid material and a solvent in which it isdissolved, a heating device that vaporizes the solvent used to preparethe gasification solution by heating that solution, and an exhaust portthat removes the vaporization product of the solvent, and

a solid sublimation chamber, either used as the solvent removal chamberor arranged communicably adjacent to it, provided with a heating devicethat gasifies a second solid material separated by removal of thesolvent by sublimation.

Moreover, in another aspect of the present invention, there is provideda process of forming a thin film comprising:

a solution preparation step wherein a first solid material is dissolvedin a solvent to prepare a gasification solution,

a solvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution,

a solid sublimation step wherein a reactive gas is generated bysublimating the second solid material, and

a film formation step wherein the thin film is deposited on a treatedsubstrate by using the reactive gas as raw material.

Furthermore, in still another aspect of the present invention, there isprovided an apparatus for forming a thin film from a solid materialcomprising:

a solvent removal chamber provided with an inlet port of a gasificationsolvent containing a first solid material and a solvent in which it isdissolved, a heating device that vaporizes the solvent used to preparethe gasification solution by heating that solution, and an exhaust portthat removes the vaporization product of the solvent,

a solid sublimation chamber, either used as the solvent removal chamberor arranged communicably adjacent to it, provided with a heating devicethat gasifies a second solid material separated by removal of thesolvent by sublimation, and

a film formation chamber wherein the thin film is deposited on a treatedsubstrate using as raw material the reactive gas generated from thesecond solid material in the solid sublimation chamber or combinationsolvent removal/solid sublimation chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart schematically depicting a preferable embodimentof a thin film formation apparatus according to the present invention;

FIG. 2 is a perspective view schematically depicting a preferableembodiment of a gasification apparatus according to the presentinvention; and

FIG. 3A to 3D are a cross-sectional view showing, in order, theoperation of another preferable embodiment of a gasification apparatusaccording to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a solid material gasification method andapparatus, as well as a process and apparatus for forming a thin filmusing a reactive gas generated from a solid material according to thegasification method and apparatus of the present invention, and each ofthese can be advantageously carried out in various embodiments.

In the practice of the present invention, there are no particularrestrictions on the technical field of gasification or thin filmformation. Examples of suitable technical fields include, but are notlimited to, the field of the production of semiconductor devices andother electronic equipment. This is because electronic equipmentrequires accurate microprocessing through the incorporation ofelectronic elements and so forth, and the importance of thin filmformation technology is therefore considerable. More specifically, whenthe gasification or thin film formation technology of the presentinvention is used, high-performance insulating films, electrode wiringfilms, semiconductor films and other thin films can be formed easily andwith good yield. A thin film formation step itself following agasification step can be advantageously carried out by using a commonlyused film deposition process and film deposition device. For example,examples of film deposition devices preferable for carrying out thepresent invention include, but are not limited to, a film depositiondevice widely used during the formation of a thin film by gasifying asolid raw material in the production of a semiconductor device, such asa sputtering device, vacuum deposition device, epitaxial growth device,PVD device or CVD device. The following provides an explanation of thepresent invention with reference to a CVD device, which is expected tobe the most effective in the present invention.

A method for gasifying a solid material according to the presentinvention is specifically composed of the following three steps:

a solution preparation step wherein a first solid material is dissolvedin a solvent to prepare a gasification solution,

a solvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, and

a solid sublimation step wherein the second solid material is gasifiedby sublimation.

Here, a first solid material refers to a solid raw material capable ofderiving a target gas in accordance with the present invention, and inparticular, a reactive gas required for forming a thin film. Thus, thereare no particular restrictions on this first solid material, and anyarbitrary solid raw material may be used alone or by mixing two or moretypes according to the composition of the target thin film (for example,compound semiconductor thin film, metal oxide thin film and so forth).In the case of using two or more types of solid raw materials incombination, that combination may be altered over a wide range.

The first solid material preferably contains at least one type oforganometallic compound if, for example, the generated reactive gas isdesired to be used for forming a thin film of a metal oxide. Examples ofsuitable organometallic compounds include, but are not limited to,Pb(DPM)₂, Zr(DPM)₄, Ti(iPrO)₂(DPM)₂, Ba(DPM)₂, Sr(DPM)₂, Ta(O-Et)₄ andBi(DPM)₃.

In the present invention, a process is not adopted in which this firstsolid material is gasified by sublimating directly as in the prior art.Namely, a first solid material is dissolved in a suitable solvent toprepare a gasification solution of a prescribed concentration. Here, inaddition to being able to easily dissolve the solid material, thesolvent is also preferably able to be vaporized easily by heating at acomparatively low temperature in a later solvent removal step.Preferable examples of solvents include tetrahydrofuran (THF), butylacetate and the like. In addition, although the first solid material canbe dissolved in this solvent at various concentrations, normally it ispreferably ultimately dissolved in the amount required for generatingthe reactive gas required for film formation. If an excess amount ofsolid material is not contained, there is hardly any reactive gasremaining at completion of film formation. Thus, maintenance of the filmdeposition device can be performed easily, and expensive raw materialsare not wasted. In general, the concentration of the first solidmaterial is within the range of about 0.03 to 0.3 mol % based on thetotal amount of gasification solution. Dissolving of the solid materialcan be advantageously carried out by a method such as adding the solidmaterial to a container containing the solvent and then mixing uniformlywith a stirring device.

After the gasification solution has been prepared in the mannerdescribed above, only the solvent is selectively removed from thatsolution. Although this solvent removal step can be carried out byvarious methods, it is advantageous to remove the solvent by heating thegasification solution to a temperature required to vaporize the solventcontained therein, and then vaporize the solvent in the stage prior tosublimation of the solid material. Although the heating temperature inthis case varies according to the type of solvent, it is normally acomparatively low temperature of about 60 to 150° C. Since solventremoval is carried out at such a low temperature, the occurrence of areaction by the solid material contained in the gasification solution,and the formation of undesirable decomposition products can beprevented, and the generation of particles can also be suppressed.Examples of heating means that can be used include an infrared heater,resistance heater and high-frequency heater.

The solvent removal step may be modified in various ways to enhancetreatment efficiency or shorten treatment time. In general, a solutiondissemination means such as a spraying tube or nozzle is provided in theupper section of the treatment chamber for removing solvent in order todisseminate the gasification solution, and heating is preferably carriedout while uniformly dispersing the gasification solution in thetreatment chamber only one or a combination of two or more of thesesolution dissemination means may be arranged. In addition, a nozzle inthe form of a straight tube in which a large number of disseminationholes are provided in its periphery may be made to extend from the uppersection to the central section of the treatment chamber. Moreover, adisc-shaped dissemination nozzle may be attached to the upper section ofthe treatment chamber, and gasification solution may be sprayed fromthat dissemination nozzle.

Alternatively, instead of spraying the gasification solution, thegasification solution may be temporarily absorbed into a solid carriercapable of temporarily retaining the gasification solution. In thiscase, the solvent can be selectively removed by heating the solidcarried impregnated with gasification solution at a low temperature, andby then continuing to heat the remaining solid carrier at a hightemperature, the entire amount can be sublimated and recovered asreactive gas in a single round of heating unaccompanied bydecomposition. In addition, in the case of using such a solid carrier,it is preferable to impregnate the solid carrier with only a fixedamount of gasification solution required for film formation. This isbecause, as only the required amount of solid material remains in thesolid carrier following vaporization of solvent, when this is heated tothe sublimation temperature of the solid material, there is virtually nosolvent or solid material remaining in the solid carrier followingrecovery of reactive gas, thereby allowing the solid carrier to bereused without requiring troublesome cleaning or other post-treatment.

The second solid material can be separated as a result of removing thesolvent in the manner described above. This solid material can normallybe separated in a form that adheres to the inner walls of the treatmentchamber, is typically adhered to the inner walls of the treatmentchamber in the form of a fine solid powder. In the case the inner wallsof the treatment chamber are porous, a portion of the solid powder istypically impregnated within the pores. In addition, according to amethod in which a solid carrier is used separately, normally, the secondsolid material can be adhered in the form of a fine solid powder to atleast the surface portion of the solid carrier. This solid carrier isalso preferably composed of a porous material. Furthermore, the removedsolvent may be recovered or reused by discharging from an exhaust portin the treatment chamber.

Next, in the solvent removal step, the second solid material separatedin the form of a fine solid powder is preferably gasified bysublimation. This solid sublimation step can be advantageously carriedout by heating to the sublimation temperature of the second solidmaterial. Although varying according to the type of solid material, theheating temperature in this case is normally a comparatively hightemperature of about 200 to 300° C. As a result of a single heating, theentire amount of the solid material is sublimated, and there is no finesolid powder remaining in the treatment chamber.

However, when carried out in accordance with the present invention, thesolvent removal step and solid sublimation step may be carried outsequentially in mutually independent treatment chambers, or they may becarried out sequentially in a single treatment chamber. Regardless ofeither approach, they can be carried out advantageously by addingmodifications to the configuration of the treatment chamber(s).Furthermore, normally, the treatment chamber is preferably composed of aclosed space. Namely, the treatment chamber may be composed in the formof a sealable reaction tank or reaction chamber made of stainless steeland so forth, and may be installed with an opening and closing gate, rawmaterial supply tube, exhaust port and other required equipment.

For example, in the case of carrying out the solvent removal step andsolid sublimation step in separate treatment chambers, arranging the twotreatment chambers adjacent to each other is preferable in terms ofenhancing treatment efficiency. It is particularly preferable to arrangethe treatment chamber of the solvent removal step and the followingtreatment chamber of the solid sublimation step separated by an openingand closing partition in combination with the use of a solid carrier foradsorbing the solid material. By adopting a shape and size that allowsmovement of the solid carrier through both treatment chambers, the solidcarrier can be transported from the solvent removal chamber to the solidsublimation chamber according to the progress of the treatment process,thereby making it possible to carry out treatment both continuously andefficiently.

A solid carrier capable of moving within the treatment chambers can beformed from various materials and in various shapes. Basically, thesolid carrier is preferably composed of a porous material foreffectively recovering the second solid material separated by removal ofsolvent. Preferable examples of porous materials include, but are notlimited to, porous metal materials such as a sintered product ofstainless steel, or a porous ceramic material such as alumina or silica.A cylindrical cell and so forth is useful for the shape of these porousmaterials in consideration of handling ease and so forth. The secondsolid material can be adhered to such a solid carrier in the form of afine solid powder.

More particularly, in the case of carrying out solvent removal in asingle treatment chamber, and carrying out solid sublimation in anothertreatment chamber adjacent to it, the gasification method of the presentinvention can be carried out according to, for example, the followingprocedure.

Supply of Gasification Solution:

A gasification solution prepared in situ or at a different location issupplied to a porous solid carrier (for example, a stainless steelsintered product as mentioned above) arranged in the treatment chamberfor removing solvent (solvent removal chamber). The solid carrier may becarried in directly to the solvent removal chamber, or may be stocked intreatment preparation chamber in front of it, and then sequentiallycarried into the solvent removal chamber from that chamber. In the caseof combining the use of a treatment preparation chamber, the carrying inof the solid carrier to the solvent removal chamber can be carried outcontinuously on demand to improve workability. As the solid carrier usedin this step is at least required to be moved from the solvent removalchamber to the adjacent solid sublimation chamber, it preferably has asuitably compact form and is capable of absorbing an adequate amount ofgasification solution in a simple operation. Preferable examples of asolid carrier include a cylindrical cell. In addition, in order to carryout treatment continuously, it is preferable that the solid carrier becomposed to be able to be moved through the treatment chambers by aconveyor or other transport means.

The supply of gasification solution to a cylindrical cell or other solidcarrier can be carried out by various methods. For example, a solutionflow path may be provided in the core section of the cylindrical cell,gasification solution is made to flow through that solution flow pathwhen the cell is placed in the solvent removal chamber, and agasification solution is uniformly dispersed throughout the entire cellthrough the pores in the cell. Alternatively, a gasification solutionmay be injected or sprayed from the periphery of a stationary orrotating solid carrier. In such cases, the gasification solution ispreferably sprayed towards the solid carrier with, for example, aspraying tube or rotating nozzle in order to uniformly absorb a suitableamount of gasification solution into the solid carrier. In this manner,an amount of gasification solution is supplied to the solvent removalchamber that is adequate for ultimately supplying a desired amount ofreactive gas. Supplying a smaller amount of gasification solution is notpreferable since it is unable to provide the desired amount of reactivegas. Conversely, supplying a greater amount of gasification solution isalso not preferable since excess solid material remains in the solidcarrier, ultimately requiring the performance of complex removal work.As a result of supplying a suitable amount of gasification solution tothe solid carrier in accordance with the present invention, not only cana stable supply of reactive gas be secured, but decomposition of the gascan be prevented and maintenance of the device can be simplified.Moreover, as the reactive gas is not contaminated by residue orparticles, there is no appearance of detrimental effects (such asinhibition of film deposition) in thin film formation using thisreactive gas.

Removal of Solvent:

After absorbing a suitable amount of gasification solution into thesolid carrier, the solvent removal chamber is heated to a temperaturethat is equal to or slightly higher than the vaporization temperature ofthe solvent of the gasification solution. A suitable heating temperatureand time are selected to facilitate efficient solvent vaporization. Forexample, in the case of using THF for the solvent, a suitable heatingtemperature and time are, for example, about 60 to 100° C. and about 3to 10 minutes. As heating at an extremely high temperature has the riskof causing sublimation of the solid material, it is preferable to avoidthe application of such temperatures. The vaporized solvent isdischarged to the outside from an exhaust port in the solvent removalchamber. As the solvent is completely removed, the second solid materialremains on the surface and inner pores of the solid carrier in the formof being adhered in the form of fine solid particles.

Sublimation of Solid Material:

Following completion of solvent removal, the solid carrier istransported from the solvent removal chamber to the following solidsublimation chamber. The solid sublimation chamber is arranged adjacentto the solvent removal chamber to improve workability and preventcontamination by impurities and so forth, and preferably employs aconstitution that allows the solid carrier to be carried in easily bythe opening and closing of a gate valve. After the solid carrier hasbeen carried into the solid sublimation chamber, the solid sublimationchamber is heated to a temperature equal to or slightly higher than thesublimation temperature of the second solid material. A suitable heatingtemperature and time are selected to carry out solid sublimationefficiently. For example, in the case of using Pb(DPM)₂ as the secondsolid material, the preferable heating temperature and heating time are,for example, about 200 to 300° C. and about 3 to 10 minutes. Due to thisheating, solid material adhered to the solid carrier is rapidlysublimated resulting in the generation of reaction gas (this gas isspecifically referred to as “reactive gas” in the present application).The generated reactive gas fills the treatment chamber, and solidmaterial adhered to the solid carrier is no longer observed. The usedsolid carrier that has been removed from the solid sublimation chambermay be reused by returning to the treatment preparation chamber orsolvent removal chamber after performing cleaning treatment asnecessary.

Discharge of Reactive Gas:

Reactive gas prepared in the manner described above is extracted from anexhaust port in the solid sublimation chamber. Although this reactivegas may be filled directly into a tank and so forth and transported to adifferent workplace or factory, it is preferable to promptly use the gasby supplying to a nearby or adjacently arranged reaction device (e.g.,CVD device). The supply of reactive gas from the solid sublimationchamber to a reaction device preferably combines the use of an inertcarrier gas such as nitrogen gas or argon gas so that the reactive gasis transferred with this carrier gas.

According to the present invention, the solvent removal step and solidsublimation step may also be advantageously carried out in a singletreatment chamber (combination solvent removal/solid sublimationchamber). In the case of this approach as well, although the previouslymentioned solid carrier may be used to adsorb the gasification solutionand be carried in and out of the treatment chamber, as the constitutionof the treatment chamber becomes complicated and treatment work becomescomplex, the solid carrier is preferably composed by means of porousinner walls (lining) of the treatment chamber.

Here, examples of porous materials useful for the lining of thetreatment chamber include, but are not limited to, porous metalmaterials such as a stainless steel sintered compact, and porous ceramicmaterials. In these porous linings, the density and pore diameter of thepores can be altered over a wide range corresponding to the desiredsolid capturing effects and subsequent solid sublimation effects.Similar to the movable solid carrier previously mentioned, the secondsolid material can also be adhered to such a lining in the form of afine solid powder.

More particularly, in the case of consistently and continuously carryingout the process from solvent removal to solid sublimation using a singletreatment chamber for both solvent removal and solid sublimation, thegasification method of the present invention can be carried out using,for example, the procedure described below.

A gasification solution either prepared locally or at a differentlocation is supplied to a treatment chamber. In this case, contrivancesare preferably made in the supply method of the gasification solution sothat a large amount of the gasification solution is uniformly absorbedinto a porous material serving as the lining of the treatment chamber.For example, a suitable method is to disseminate the gasificationsolution in the treatment chamber with a spraying tube or rotatingnozzle and so forth. In this manner, an amount of gasification solutionis supplied to the treatment chamber that is adequate for ultimatelysupplying the desired amount of reactive gas. The supply of a smalleramount of gasification solution is not desirable as the desired amountof reactive gas cannot be obtained. Conversely, the supply of a greateramount of gasification solution is not desirable as excess solidmaterial ends up remaining on the inner walls of the treatment chamber,thereby ultimately requiring bothersome removal work. If a suitableamount of gasification solution is supplied in accordance with thepresent invention, not only can a stable supply of reactive gas besecured, but gas decomposition can be prevented and maintenance of thedevice can be simplified. Moreover, as the reactive gas is notcontaminated by residue or particles, there is no appearance ofdetrimental effects (such as inhibition of film deposition) in thin filmformation using this reactive gas.

Removal of Solvent:

After supplying a suitable amount of gasification solution to thetreatment chamber, the treatment chamber is heated to a temperature thatis equal to or slightly higher than the vaporization temperature of thesolvent. A suitable heating temperature and time are selected tofacilitate efficient solvent vaporization. For example, in the case ofusing THF for the solvent, a suitable heating temperature and time are,for example, about60 to

100° C. and about 3 to 10 minutes. Since heating at an extremely hightemperature has the risk of causing sublimation of the solid material,it is preferable to avoid the application of such temperatures. Thevaporized solvent is discharged to the outside from an exhaust port. Asthe solvent is completely removed, the second solid material remains onthe inner walls of the treatment chamber in the form of being adhered inthe form of fine solid particles.

Sublimation of Solid Material:

The treatment chamber is heated to a temperature equal to or slightlyhigher than the sublimation temperature of the second solid material. Asuitable heating temperature and time are selected to carryout solidsublimation efficiently. For example, in the case of using Pb(DPM)₂ asthe second solid material, the preferable heating temperature andheating time are, for example, about 200 to 300° C. and about 3 to 10minutes. Due to this heating, solid material adhered to the inner wallsof the treatment chamber is rapidly sublimated resulting in thegeneration of reaction gas (this gas is specifically referred to as“reactive gas” in the present application). The generated reactive gasfills the treatment chamber, and solid material adhered to the innerwalls of the treatment chamber is no longer observed.

Discharge of Reactive Gas:

A reactive gas prepared in the manner described above is extracted froman exhaust port in the treatment chamber. Although this reactive gas maybe filled directly into a tank and so forth and transported to adifferent workplace or factory, it is preferable to promptly use the gasby supplying to a nearby or adjacently arranged reaction device. Thesupply of reactive gas from the treatment chamber to a reaction devicepreferably combines the use of an inert carrier gas such as nitrogen gasor argon gas so that the reactive gas is transferred with this carriergas.

In the case of discharged reactive gas from the treatment chamber, thereis hardly any solid material remaining in the treatment chamber. As aresult, a treatment chamber that has been used in the above series oftreatment steps can again be immediately used in the next series oftreatment steps, or can be used in the next series of treatment stepsfollowing a simple maintenance treatment.

The apparatus for gasifying a solid material according to the presentinvention is provided with treatment chambers required to carry out eachof the treatment steps corresponding to the previously describedgasification method according to the present invention, namely:

a solvent removal chamber provided with an inlet port of a gasificationsolvent containing a first solid material and a solvent in which it isdissolved, a heating device that vaporizes the solvent used to preparethe gasification solution by heating that solution, and an exhaust portthat removes the vaporization product of the solvent, and,

a solid sublimation chamber either also used as the solvent removalchamber or arranged communicably adjacent to it, and provided with aheating device that gasifies a second solid material separated byremoval of the solvent by sublimation.

Although it can be easily understood from the previous explanation ofthe gasification method, the following provides a supplementaryexplanation of a summary of preferable constitutions of each treatmentchamber.

The solvent removal chamber and solid sublimation chamber, orcombination solvent removal/solid sublimation chamber can each have aconstitution similar to a treatment chamber like that used ingasification devices of the prior art. These treatment chambers arepreferably composed of a closed space in particular, and thus, a sealedcontainer, tank, chamber and so forth made of a strong metal materialsuch as stainless steel is preferable.

Although the solvent removal chamber and solid sublimation chamber maybe composed mutually independently and allow a solid carrier to betransported through a connecting pipe and so forth, the solvent removalchamber and following solid sublimation chamber are preferably arrangedadjacent to each other separated by an opening and closing partition(such as a gate valve).

The solvent removal chamber and solid sublimation chamber, orcombination solvent removal/solid sublimation chamber, are each requiredto be provided with a heating device for vaporizing the solvent andsublimating the solid. Here, the heating device of a combination solventremoval/solid sublimation chamber is preferably provided with a heatingmechanism that heats the gasification solution and vaporizes the solventused to prepare it, and a heating mechanism that gasifies the secondsolid material by sublimation. Thus, a heating device is preferablyprovided that allows the heating temperature to be adjusted to anarbitrary set temperature.

There are no particular restrictions on the heating device, examples ofwhich include an infrared heater, a resistance heater and ahigh-frequency heater as previously explained. These heating devices maybe arranged within each treatment chamber, on the chamber walls oraround the external periphery corresponding to the design of thetreatment chambers and so forth. Normally, arranging the heating deviceeither on the chamber walls or around the external periphery so as tosurround the treatment chamber is useful in terms of heating efficiencyand workability.

The solvent removal chamber or combination solvent removal/solidsublimation chamber may be provided with various supply means forsupplying gasification solution to the treatment chamber. For example, adissemination means that introduces a gasification solution in the formof fine droplets, such as a spraying tube or nozzle, is preferablyprovided in the upper section of the treatment chamber as previouslyexplained. Such a dissemination means may also be arranged on the sidesor bottom of the treatment chamber as necessary because it furtherenhances the dissemination efficiency of the gasification solution. Inaddition, as is explained next, in the case of using a movable solidcarrier, a special supply means may be provided that injects or suppliesgasification solution to the solid carrier directly.

In addition, the solvent removal chamber or combination solventremoval/solid sublimation chamber preferably additionally has a solidcarrier that holds the second solid material in the form of a fine solidpowder. The solid carrier used here is preferably a porous material suchas a stainless steel sintered compact, as was previously explained.

As was previously explained, in accordance with one preferableembodiment, the solid carrier is a portable solid carrier that can bemoved from the solvent removal chamber to the solid sublimation chamber.An example of such a solid carrier is a cylindrical porous cell. Atransport means such as a conveyor belt or a chuck mechanism ispreferably used in combination for facilitating movement of the solidcarrier.

According to another preferable embodiment, the solid carrier ispreferably the porous inner walls, namely a lining, of the combinationsolvent removal/solid sublimation chamber. Examples of lining materialsinclude porous metal materials and ceramic materials as previouslyexplained. Although the lining normally covers the entire surface of thetreatment chamber, it may also only partially cover the surface of thetreatment chamber as necessary.

The solvent removal chamber or combination solvent removal/solidsublimation chamber as described above each have an exhaust port fortransferring reactive gas generated by sublimation of the second solidmaterial to a following treatment chamber. In addition, an inlet portfor an inert carrier gas for transporting together with the reactive gasis additionally preferably provided in combination with this exhaustport.

The present invention also resides in a process and apparatus forforming a thin film from a solid material. The thin film formationprocess of the present invention comprises, in addition to the followingthree steps essential for the previously described gasification methodaccording to the present invention, namely:

a solution preparation step wherein a first solid material is dissolvedin a solvent to prepare a gasification solution,

a solvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, and

a solid sublimation step wherein a reactive gas is generated bysublimating the second solid material,

a film formation step wherein the thin film is deposited on a treatedsubstrate by using the reactive gas generated in the solid sublimationstep as raw material. The solution preparation step, solvent removalstep and solid sublimation step can each be carried out advantageouslyin the manner previously described.

There are no particular restrictions on the film formation step,examples of which include sputtering, vacuum vapor deposition, epitaxialgrowth, PVD and CVD as previously mentioned. In the case of CVD, forexample, after the treated substrate on which the thin film is to beformed (such as a silicon wafer) is arranged inside a vacuum-compatibleCVD device, the reactive gas generated in the solid sublimation step issupplied to the substrate either alone or in combination with anotherreactive gas. The molecules of the reactive gas are then excited bythermal energy, plasma discharge or laser radiation and so forth,causing the occurrence of a chemical reaction for forming the film. Athin film of a desired film thickness is thus formed on the surface ofthe substrate. As the amount of reactive gas supplied to the CVD deviceis preliminarily controlled to the amount required for film formation inaccordance with the controlled gasification method of the presentinvention, the thickness of this thin film is constant and itscomposition is uniform.

Moreover, the present invention resides in an apparatus for carrying outthe process for forming a thin film as described above, namely anapparatus for forming a thin film from a solid material comprising:

a solvent removal chamber provided with an inlet port for a gasificationsolvent containing a first solid material and a solvent in which it isdissolved, a heating device that vaporizes the solvent used to preparethe gasification solution by heating that solution, and an exhaust portthat removes the vaporization product of the solvent,

a solid sublimation chamber either also used as the solvent removalchamber or arranged communicably adjacent to it, and provided with aheating device that gasifies a second solid material separated byremoval of the solvent by sublimation, and

a film formation chamber wherein the thin film is deposited on a treatedsubstrate using as raw material the reactive gas generated from thesecond solid material in the solid sublimation chamber or combinationsolvent removal/solid sublimation chamber.

In the thin film formation apparatus of the present invention, althougharbitrary modifications may be respectively added to the solvent removalchamber and solid sublimation chamber as necessary, they normally may becomposed in the same manner as the treatment chambers used in thegasification apparatus previously described.

Although there are no particular restrictions on the film formationchamber, it includes a sputtering device, a vacuum vapor depositiondevice, an epitaxial growth device, a PVD device or a CVD device, and soforth, as previously described. A CVD device, for example, may beprovided with a vacuum-compatible reaction chamber, a holder that holdsthe substrate to be treated, a shower head for supplying the reactivegas and an exhaust port. Furthermore, since CVD devices and other filmformation devices have already been explained in detail in varioustechnical documents, those documents should be referred to for furtherdetails.

EXAMPLES

Examples of the present invention will be described hereinafter withreference to the drawings. Furthermore, it should be noted that thepresent invention is not limited to these examples.

FIG. 1 is a flow chart schematically depicting a preferable embodimentof a thin film formation apparatus according to the present invention.In thin film formation apparatus 2 shown in FIG. 1, the gasificationapparatus 1 of the present invention is arranged in its prior stage, andgasification apparatus 1 employs a two chamber system consisting ofsolvent removal chamber 20 and solid sublimation chamber 30. Theconstitution of gasification apparatus 1 is also explained with theperspective view shown in FIG. 2. Furthermore, it should be understoodthat the gasification apparatus 1 of FIG. 2 is shown with a portion ofthe apparatus omitted to simplify the explanation.

Gasification apparatus 1 is provided with the major elements oftreatment preparation chamber 10, solvent removal chamber 20 and solidsublimation chamber 30. As shown in the drawing, a large number ofcylindrical raw material cells 11 composed of stainless steel sinteredproduct are installed in treatment preparation chamber 10. Each rawmaterial cell 11 is 30 mm in diameter and 80 mm in length. Raw materialcells 11 are transported one at a time to solvent removal chamber 20. Asuitable amount of gasification solution S required for film formationis dropped from an accessory gasification solution injection port 21onto raw material cell 11 that has been transported to solvent removalchamber 20. The gasification solution is a solution that is prepared bydissolving a solid film formation raw material in a solvent, and may beprepared in situ at the work site or prepared at a different work siteor factory, and may be connected to injection port 21 shown in thedrawing. The film formation raw material used here (the first solidmaterial as referred to in the present invention) is Pb(DPM)₂, and isdissolved in THF at a concentration of 0.3 mol %. As the raw materialcell 11 is porous, the gasification solution is uniformly absorbed intothe cell.

Following completion of absorption of the gasification solution, thesolvent removal chamber is heated to about 90° C. with an accessoryheater (resistance heating heater) to vaporize only the solvent of thegasification solution. As the solvent is removed from raw material cell11, the raw material solid (the second solid material as referred to inthe present invention) precipitates in the form of a fine solid.Furthermore, as the heating performed here is only the heating requiredto vaporize the solvent, there is no occurrence of decomposition and soforth of the raw material solid, and decomposition products that causethe formation of particles are not formed. The vaporized solvent ischarged to the outside from an exhaust port 23.

After the raw material solid has finished precipitating, a gate valve 25that separates solvent removal chamber 20 and solid sublimation chamber30 opens, raw material cell 11 is moved from solvent removal chamber 20to solid sublimation chamber 30, and gate valve 25 again closes.Although not shown in the drawing, a belt conveyor is used to move rawmaterial cell 11.

Solid sublimation chamber 30 is heated to about

260° C. by an accessory heater (resistance heating heater) 32 in thestate in which solid sublimation chamber 30 is sealed. The raw materialsolid adhered to raw material cell 11 is sublimated, and the gas (thereactive gas as referred to in the present invention) fills the insideof the chamber. After a carrier gas G introduced from carrier gas inlettube 31 is expelled, the generated reactive gas is led to thin filmformation device 2 after passing through conduit 33, flow meter (MFC) 34and conduit 51. Flow meter 34 is able to lead the reactive gas requiredfor film formation into thin film formation apparatus 2 whilecontrolling its flow rate.

Thin film formation apparatus 2 is a normal pressure CVD device providedwith a vacuum-compatible reaction chamber 50, a holder 53 equipped witha heater for holding a treated substrate 55 (here, a silicon substrate),a shower head 52 for supplying the reactive gas, and an exhaust port 54.When film formation is carried out under prescribed conditions in thisthin film formation apparatus 2, a thin oxide film of Pb(DPM)₂ is formedat a uniform thickness on silicon substrate 55 without being accompaniedby particle contamination and so forth.

As there is no residual accumulation of gasification solution S insidesolvent removal chamber 20 used in this embodiment, and fine particlesof raw material solid do not remain in solid sublimation chamber 30 orraw material cell 11, treatment is able to proceed to the next rawmaterial solid gasification process or thin film formation processwithout having to clean these treatment chambers or after performing asimple cleaning operation. Raw material cell 11 can also be returned tothe treatment preparation chamber without requiring any cleaningtreatment whatsoever.

FIGS. 3A to 3D are a cross-sectional view showing the actual order inwhich a combination solvent removal/solid sublimation chamber is used inanother preferable embodiment of a gasification apparatus according tothe present invention. This combination solvent removal/solidsublimation chamber 40 is composed of a sealed tank made of stainlesssteel, and its inner walls are lined with a metal sponge (stainlesssteel sintered product) lining 41. The thickness of lining 41 is about20 mm. As shown in each drawing, a first conduit 42 provided with avalve 43, a second conduit 45 provided with a valve 46, and a thirdconduit provided with a valve 47 and a flow meter (MFC) 44 are connectedto combination solvent removal/solid sublimation chamber 40. The end offirst conduit 42 terminates in the upper section of combination solventremoval/solid sublimation chamber 40, and a dissemination nozzle 49 isattached thereto.

A raw material solid can be gasified according to the followingprocedure using the combination solvent removal/solid sublimationchamber 40 shown in the drawing.

To begin with, as shown in FIG. 3A, after closing valve 47 ofcombination solvent removal/solid sublimation chamber 40, a suitableamount of gasification solution S required for film formation isintroduced into combination solvent removal/solid sublimation chamber 40from first conduit 42. Gasification solution S is the product ofdissolving a raw material solid (referred to as a first solid materialin the present invention) in the form of Pb(DPM)₂ in THF to aconcentration of 0.3 mol %. Gasification solution S is dispersed withincombination solvent removal/solid sublimation chamber 40 bydissemination nozzle 49, and uniformly absorbed into lining 41.Discharge of excess gas is carried out with second conduit 45 throughopened valve 46.

As shown in FIG. 3B, after absorbing the gasification solution intolining 41, solvent is removed in the state in which valves 43 and 47 areclosed. Only the solvent of gasification solution S is removed byheating combination solvent removal/solid sublimation chamber 40 atabout 90° C. with an accessory heater (resistance heating heater, notshown). As the solvent is removed from lining 41, the raw material solid(a second solid material as referred to in the present invention)precipitates on the surface of lining 41 in the form of fine solidparticles Si. Furthermore, as the heating carried out here is theheating required to vaporize the solvent, there is no decomposition andso forth of the raw material solid, and decomposition products thatcause the generation of particles are not formed. As valve 46 is open,the vaporized solvent is discharged to the outside from second conduit45.

Following completion of precipitation of the raw material solid, asshown in FIG. 3C, valves 43, 46 and 47 are closed to seal combinationsolvent removal/solid sublimation chamber 40. Combination solventremoval/solid sublimation chamber 40 is then heated to about 260° C. byan accessory heater (resistance heating heater also used for thepreviously mentioned solvent removal) while maintaining this sealedstate. The raw material solid adhered to lining 41 is sublimated, andthat gas (referred to as reactive gas in the present invention) S2 fillsthe inside of the chamber.

Then, as shown in FIG. 3D, the generated reactive gas S2 is discharged.Valves 43 and 47 are opened while leaving valve 46 closed. When acarrier gas (here, nitrogen gas) G is introduced from the first conduitinto combination solvent removal/solid sublimation chamber 40, reactivegas S2 is expelled by carrier gas G, discharged through valve 47, flowmeter (MFC) 44 and third conduit 51, and sent to a following filmformation device (not shown).

As there is no gasification solution or fine particles of raw materialsolid remaining inside combination solvent removal/solid sublimationchamber 40 after going through the treatment process described above,the process is able to proceed to the gasification process of the nextraw material solid without having to clean the inside of the chamber oronly perform simple cleaning work.

As has been described in detail above, according to the gasificationmethod and apparatus of the present invention, a solid material can begasified easily and in a stable manner, and the resulting reactive gascan be advantageously used in a subsequent film formation step.

In addition, according to the film formation process and apparatus ofthe present invention, a thin film can be formed both easily and in astable manner without being accompanied by deterioration of compositionor properties during thin film formation, or the generation of debrisand particles.

Moreover, as the thin film that is formed does not contain defects, theuse of the present invention allows the production of high-performancesemiconductor devices and other electronic devices with a good yield.

Moreover, according to the present invention, by preparing a fixedamount of raw material solution required for film formation, andgasifying this solution following solvent removal and sublimation of thesolid raw material, the formation of raw material decomposition productscan be suppressed and, as only the required amount of raw material isgasified, decomposition of the raw material gas can be prevented, and astable supply of raw material gas can be secured.

1. A method for gasifying a solid material comprising: a solutionpreparation step wherein a first solid material is dissolved in asolvent to prepare a gasification solution, a solvent removal stepwherein a second solid material is separated by removing the solventused to prepare the gasification solution from that solution, and asolid sublimation step wherein the second solid material is gasified bysublimation.
 2. A solid material gasification method as set forth inclaim 1, wherein the solvent removal step and the solid sublimation stepare carried out sequentially in mutually independent treatment chambers.3. A solid material gasification method as set forth in claim 2, whereinthe treatment chamber of the solvent removal step and the treatmentchamber of the following solid sublimation step are arranged separatedby an opening and closing partition.
 4. A solid material gasificationmethod as set forth in claim 1, wherein the solvent removal step and thesolid sublimation step are carried out sequentially in a singletreatment chamber.
 5. A solid material gasification method as set forthin claim 2, wherein the treatment chambers are composed of closedspaces.
 6. A solid material gasification method as set forth in claim 2,wherein the gasification solution is introduced into the treatmentchamber in the form of fine droplets, and the solvent is removed withinsaid treatment chamber.
 7. A solid material gasification method as setforth in claim 1, wherein the second solid material is adhered to asolid carrier in the form of a fine solid powder in the solvent removalstep.
 8. A solid material gasification method as set forth in claim 7,wherein the solid carrier is a porous material arranged within thetreatment chamber.
 9. A solid material gasification method as set forthin claim 8, wherein the porous material is made to move within thetreatment chamber according to the progress of the treatment steps. 10.A solid material gasification method as set forth in claim 8, whereinthe solid carrier is a porous inner wall of the treatment chamber.
 11. Asolid material gasification method as set forth in claim 7, wherein thesolid carrier is composed of a porous metal material.
 12. A solidmaterial gasification method as set forth in claim 7, wherein the solidcarrier is composed of a porous ceramic material.
 13. A solid materialgasification method as set forth in claim 1, wherein the solvent isselectively removed by heating the gasification solution to atemperature required for vaporization of the solvent.
 14. A solidmaterial gasification method as set forth in claim 1, wherein the secondsolid material is sublimated by heating to its sublimation temperature.15. A solid material gasification method as set forth in claim 1,wherein reactive gas generated by sublimation of the second solidmaterial is transferred to the next treatment step together with acarrier gas.
 16. A solid material gasification method as set forth inclaim 1, wherein the first solid material is composed of at least onetype of organometallic compound.
 17. A solid material gasificationmethod as set forth in claim 16, wherein the organometallic compound isselected from the group consisting of Pb(DPM)₂, Zr(DPM)₄,Ti(iPrO)₂(DPM)₂, Ba(DPM)₂, Sr(DPM)₂, Ta(O-Et)₄ and Bi(DPM)₃.
 18. Aprocess of forming a thin film comprising: a solution preparation stepwherein a first solid material is dissolved in a solvent to prepare agasification solution, a solvent removal step wherein a second solidmaterial is separated by removing the solvent used to prepare thegasification solution from that solution, a solid sublimation stepwherein a reactive gas is generated by sublimating the second solidmaterial, and a film formation step wherein the thin film is depositedon a treated substrate by using the reactive gas as raw material.
 19. Aprocess of forming a thin film comprising: a solution preparation stepwherein a first solid material is dissolved in a solvent to prepare agasification solution, a solvent removal step wherein a second solidmaterial is separated by removing the solvent used to prepare thegasification solution from that solution, a solid sublimation stepwherein a reactive gas is generated by sublimating the second solidmaterial, and a film formation step wherein the thin film is depositedon a treated substrate by using the reactive gas as raw material;wherein the reactive gas is generated by the gasification methoddescribed in claim
 2. 20. A process of forming a thin film comprising: asolution preparation step wherein a first solid material is dissolved ina solvent to prepare a gasification solution, a solvent removal stepwherein a second solid material is separated by removing the solventused to prepare the gasification solution from that solution, a solidsublimation step wherein a reactive gas is generated by sublimating thesecond solid material, and a film formation step wherein the thin filmis deposited on a treated substrate by using the reactive gas as rawmaterial; wherein the reactive gas is generated by the gasificationmethod described in claim
 3. 21. A process of forming a thin filmcomprising: a solution preparation step wherein a first solid materialis dissolved in a solvent to prepare a gasification solution, a solventremoval step wherein a second solid material is separated by removingthe solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 4. 22. A process of forming athin film comprising: a solution preparation step wherein a first solidmaterial is dissolved in a solvent to prepare a gasification solution, asolvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 5. 23. A process of forming athin film comprising: a solution preparation step wherein a first solidmaterial is dissolved in a solvent to prepare a gasification solution, asolvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 6. 24. A process of forming athin film comprising: a solution preparation step wherein a first solidmaterial is dissolved in a solvent to prepare a gasification solution, asolvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 7. 25. A process of forming athin film comprising: a solution preparation step wherein a first solidmaterial is dissolved in a solvent to prepare a gasification solution, asolvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 8. 26. A process of forming athin film comprising: a solution preparation step wherein a first solidmaterial is dissolved in a solvent to prepare a gasification solution, asolvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 9. 27. A process of forming athin film comprising: a solution preparation step wherein a first solidmaterial is dissolved in a solvent to prepare a gasification solution, asolvent removal step wherein a second solid material is separated byremoving the solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 10. 28. A process of forminga thin film comprising: a solution preparation step wherein a firstsolid material is dissolved in a solvent to prepare a gasificationsolution, a solvent removal step wherein a second solid material isseparated by removing the solvent used to prepare the gasificationsolution from that solution, a solid sublimation step wherein a reactivegas is generated by sublimating the second solid material, and a filmformation step wherein the thin film is deposited on a treated substrateby using the reactive gas as raw material; wherein the reactive gas isgenerated by the gasification method described in claim
 11. 29. Aprocess of forming a thin film comprising: a solution preparation stepwherein a first solid material is dissolved in a solvent to prepare agasification solution, a solvent removal step wherein a second solidmaterial is separated by removing the solvent used to prepare thegasification solution from that solution, a solid sublimation stepwherein a reactive gas is generated by sublimating the second solidmaterial, and a film formation step wherein the thin film is depositedon a treated substrate by using the reactive gas as raw material;wherein the reactive gas is generated by the gasification methoddescribed in claim
 12. 30. A process of forming a thin film comprising:a solution preparation step wherein a first solid material is dissolvedin a solvent to prepare a gasification solution, a solvent removal stepwherein a second solid material is separated by removing the solventused to prepare the gasification solution from that solution, a solidsublimation step wherein a reactive gas is generated by sublimating thesecond solid material, and a film formation step wherein the thin filmis deposited on a treated substrate by using the reactive gas as rawmaterial; wherein the reactive gas is generated by the gasificationmethod described in claim
 13. 31. A process of forming a thin filmcomprising: a solution preparation step wherein a first solid materialis dissolved in a solvent to prepare a gasification solution, a solventremoval step wherein a second solid material is separated by removingthe solvent used to prepare the gasification solution from thatsolution, a solid sublimation step wherein a reactive gas is generatedby sublimating the second solid material, and a film formation stepwherein the thin film is deposited on a treated substrate by using thereactive gas as raw material; wherein the reactive gas is generated bythe gasification method described in claim
 14. 32. A process of forminga thin film comprising: a solution preparation step wherein a firstsolid material is dissolved in a solvent to prepare a gasificationsolution, a solvent removal step wherein a second solid material isseparated by removing the solvent used to prepare the gasificationsolution from that solution, a solid sublimation step wherein a reactivegas is generated by sublimating the second solid material, and a filmformation step wherein the thin film is deposited on a treated substrateby using the reactive gas as raw material; wherein the reactive gas isgenerated by the gasification method described in claim
 15. 33. Aprocess of forming a thin film comprising: a solution preparation stepwherein a first solid material is dissolved in a solvent to prepare agasification solution, a solvent removal step wherein a second solidmaterial is separated by removing the solvent used to prepare thegasification solution from that solution, a solid sublimation stepwherein a reactive gas is generated by sublimating the second solidmaterial, and a film formation step wherein the thin film is depositedon a treated substrate by using the reactive gas as raw material;wherein the reactive gas is generated by the gasification methoddescribed in claim
 16. 34. A process of forming a thin film comprising:a solution preparation step wherein a first solid material is dissolvedin a solvent to prepare a gasification solution, a solvent removal stepwherein a second solid material is separated by removing the solventused to prepare the gasification solution from that solution, a solidsublimation step wherein a reactive gas is generated by sublimating thesecond solid material, and a film formation step wherein the thin filmis deposited on a treated substrate by using the reactive gas as rawmaterial; wherein the reactive gas is generated by the gasificationmethod described in claim 17.